As light energy is absorbed within the skin, light can be used to achieve desired clinical results. In particular, light has been used to remove hair, eliminate leg veins, remove or reduce the color of tattoos. In addition, water absorption of light energy transforming light into heat energy has been used for laser ablation of the skin surface or for use of lasers as cutting instruments. Plastic surgeons, dermatologists and their patients continually search for new and improved methods to alter the appearance of the skin.
Presently, all of the methods using either lasers or intense pulsed light in treating the skin require that the emitted energy to be absorbed selectively within the skin. The object that absorbs that energy, is termed a chromophore. The chromophore can be a true color such as black or brown, or red. Alternatively, this is a molecule absorbing energy, such as water or protein complex. Selective chromophore absorption is the absorption of a particular type of light energy by a chromophore. A clinical treatment can work because of selective chromophore absorption, wherein light energy is selectively absorbed by a particular component of the skin. If light energy were non-selectively absorbed throughout the skin, damage and injury would occur. The current problem in present laser and intense light treatment of the skin is that the clinical gain is often limited because the amount of beneficial skin selective chromophore absorption is always limited by the amount of non-selective unwanted absorption of energy throughout the skin.